TY - JOUR
T1 - Dual function of pancreatic endoplasmic reticulum kinase in tumor cell growth arrest and survival
AU - Ranganathan, Aparna C.
AU - Ojha, Shishir
AU - Kourtidis, Antonis
AU - Conklin, Douglas S.
AU - Aguirre-Ghiso, Julio A.
PY - 2008/5/1
Y1 - 2008/5/1
N2 - Pancreatic endoplasmic reticulum kinase (PERK)-eIF2α signaling, a component of the endoplasmic reticulum (ER) stress response, has been proposed as a therapeutic target due to its importance to cell survival in hypoxic tumors. In this study, we show that in addition to promoting survival, PERK can also suppress tumor growth of advanced carcinomas. Our results show that in squamous carcinoma T-HEp3 cells, which display low PERK-eIF2α signaling, inducible activation of an Fv2E-PERK fusion protein results in a strong G 0-G1 arrest in vitro. Most importantly, Fv2E-PERK activation, in addition to promoting survival in vitro, inhibits T-HEp3 and SW620 colon carcinoma growth in vivo. Increased PERK activation is linked to enhanced p-eIF2α levels, translational repression, and a decrease in Ki67, pH 3, and cycD1/D3 levels, but not to changes in angiogenesis or apoptosis. Experimental reduction of PERK activity, or overexpression of GADD34 in a spontaneously arising in vivo quiescent variant of HEp3 cells that displays strong basal PERK-eIF2α activation, reverts their quiescent phenotype. We conclude that the growth-inhibitory function of PERK is preserved in tumors and upon proper reactivation can severely inhibit tumor growth through induction of quiescence. This is an important consideration in the development of PERK-based therapies, as its inhibition may facilitate the proliferation of slow-cycling or dormant tumor cells.
AB - Pancreatic endoplasmic reticulum kinase (PERK)-eIF2α signaling, a component of the endoplasmic reticulum (ER) stress response, has been proposed as a therapeutic target due to its importance to cell survival in hypoxic tumors. In this study, we show that in addition to promoting survival, PERK can also suppress tumor growth of advanced carcinomas. Our results show that in squamous carcinoma T-HEp3 cells, which display low PERK-eIF2α signaling, inducible activation of an Fv2E-PERK fusion protein results in a strong G 0-G1 arrest in vitro. Most importantly, Fv2E-PERK activation, in addition to promoting survival in vitro, inhibits T-HEp3 and SW620 colon carcinoma growth in vivo. Increased PERK activation is linked to enhanced p-eIF2α levels, translational repression, and a decrease in Ki67, pH 3, and cycD1/D3 levels, but not to changes in angiogenesis or apoptosis. Experimental reduction of PERK activity, or overexpression of GADD34 in a spontaneously arising in vivo quiescent variant of HEp3 cells that displays strong basal PERK-eIF2α activation, reverts their quiescent phenotype. We conclude that the growth-inhibitory function of PERK is preserved in tumors and upon proper reactivation can severely inhibit tumor growth through induction of quiescence. This is an important consideration in the development of PERK-based therapies, as its inhibition may facilitate the proliferation of slow-cycling or dormant tumor cells.
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U2 - 10.1158/0008-5472.CAN-07-6215
DO - 10.1158/0008-5472.CAN-07-6215
M3 - Article
C2 - 18451152
AN - SCOPUS:44849124523
SN - 0008-5472
VL - 68
SP - 3260
EP - 3268
JO - Cancer research
JF - Cancer research
IS - 9
ER -
